diff --git a/lib/git/aliases.sh b/lib/git/aliases.sh
index 2d6a6b87..09485402 100644
--- a/lib/git/aliases.sh
+++ b/lib/git/aliases.sh
@@ -75,7 +75,7 @@ __git_alias () {
     fi
 
     alias $alias_str="$cmd_prefix $cmd${cmd_args:+ }${cmd_args[*]}"
-    if [ "$shell" = "bash" ]; then
+    if breeze_shell_is "bash"; then
       __define_git_completion "$alias_str" "$cmd"
       complete -o default -o nospace -F _git_"$alias_str"_shortcut "$alias_str"
     fi
@@ -177,10 +177,9 @@ if [ "$git_setup_aliases" = "yes" ]; then
   _alias "$git_pull_request_alias"        'gh pr'
 fi
 
-
-
+# TODO(ghthor): apply these same fixes for NixOS
 # Tab completion
-if [ $shell = "bash" ]; then
+if breeze_shell_is "bash"; then
   # Fix to preload Arch bash completion for git
   [[ -s "/usr/share/git/completion/git-completion.bash" ]] && source "/usr/share/git/completion/git-completion.bash"
   # new path in Ubuntu 13.04
diff --git a/lib/git/branch_shortcuts.sh b/lib/git/branch_shortcuts.sh
index 0a195f2a..467b2038 100644
--- a/lib/git/branch_shortcuts.sh
+++ b/lib/git/branch_shortcuts.sh
@@ -47,7 +47,7 @@ __git_alias "$git_branch_delete_alias"       "_scmb_git_branch_shortcuts" "-d"
 __git_alias "$git_branch_delete_force_alias" "_scmb_git_branch_shortcuts" "-D"
 
 # Define completions for git branch shortcuts
-if [ "$shell" = "bash" ]; then
+if breeze_shell_is "bash"; then
   for alias_str in $git_branch_alias $git_branch_all_alias $git_branch_move_alias $git_branch_delete_alias; do
     __define_git_completion $alias_str branch
     complete -o default -o nospace -F _git_"$alias_str"_shortcut $alias_str
diff --git a/lib/git/fallback/status_shortcuts_shell.sh b/lib/git/fallback/status_shortcuts_shell.sh
index 0a103870..22cdda66 100755
--- a/lib/git/fallback/status_shortcuts_shell.sh
+++ b/lib/git/fallback/status_shortcuts_shell.sh
@@ -53,10 +53,14 @@ git_status_shortcuts() {
     echo -e "$c_dark#$c_rst On branch: $c_branch$branch$c_rst  $c_dark|  [$c_rst*$c_dark]$c_rst => \$$git_env_char*\n$c_dark#$c_rst"
 
     for line in $git_status; do
-      if [[ $shell == *bash ]]; then
-        x=${line:0:1}; y=${line:1:1}; file=${line:3}
+      if breeze_shell_is "bash"; then
+        x=${line:0:1}
+        y=${line:1:1}
+        file=${line:3}
       else
-        x=$line[1]; y=$line[2]; file=$line[4,-1]
+        x=$line[1]
+        y=$line[2]
+        file=$line[4,-1]
       fi
 
       # Index modification states
diff --git a/lib/git/keybindings.sh b/lib/git/keybindings.sh
index 4bbca42b..28865915 100644
--- a/lib/git/keybindings.sh
+++ b/lib/git/keybindings.sh
@@ -10,9 +10,9 @@
 # See [here](http://qntm.org/bash#sec1) for info about why I wanted a prompt.
 
 # Cross-shell key bindings
-_bind(){
+_bind() {
   if [ -n "$1" ]; then
-    if [[ $shell == "zsh" ]]; then
+    if breeze_shell_is "zsh"; then
       bindkey -s "$1" "$2"
     else # bash
       bind "\"$1\": $2"
@@ -24,11 +24,11 @@ _bind(){
 if [[ "$git_keyboard_shortcuts_enabled" = "true" ]]; then
   case "$-" in
   *i*)
-      if [ -n "$ZSH_VERSION" ]; then
-        RETURN_CHAR="^M"
-      else
-        RETURN_CHAR="\n"
-      fi
+    if [ -n "$ZSH_VERSION" ]; then
+      RETURN_CHAR="^M"
+    else
+      RETURN_CHAR="\n"
+    fi
 
       # Uses emacs style keybindings, so vi mode is not supported for now
       if ! set -o | grep -q '^vi .*on$'; then
diff --git a/lib/git/repo_index.sh b/lib/git/repo_index.sh
index fa60797a..51622cfb 100644
--- a/lib/git/repo_index.sh
+++ b/lib/git/repo_index.sh
@@ -79,8 +79,8 @@ function git_index() {
       echo
 
     # If $1 starts with '/', change to top-level directory within $GIT_REPO_DIR
-    elif ([ $shell = "bash" ] && [ "${1:0:1}" = "/" ]) || \
-         ([ $shell = "zsh" ]  && [ "${1[1]}"  = "/" ]); then
+    elif (breeze_shell_is "bash" && [ "${1:0:1}" = "/" ]) || \
+         (breeze_shell_is "zsh"  && [ "${1[1]}"  = "/" ]); then
       if [ -d "$GIT_REPO_DIR$1" ]; then
         builtin cd "$GIT_REPO_DIR$1"
       fi
@@ -278,7 +278,7 @@ function _git_index_batch_cmd() {
 }
 
 
-if [ $shell = 'bash' ]; then
+if breeze_shell_is "bash"; then
 	# Bash tab completion function for git_index()
 	function _git_index_tab_completion() {
 		_check_git_index
diff --git a/lib/git/shell_shortcuts.sh b/lib/git/shell_shortcuts.sh
index de1693dc..3b8f2289 100644
--- a/lib/git/shell_shortcuts.sh
+++ b/lib/git/shell_shortcuts.sh
@@ -127,7 +127,7 @@ if [ "$shell_ls_aliases_enabled" = "true" ] && builtin command -v ruby >/dev/nul
       ll_output="$(CLICOLOR_FORCE=1 "${ll_command[@]}" -lG "$@")"
     fi
 
-    if [[ $shell == "zsh" ]]; then
+    if breeze_shell_is "zsh"; then
       # Ensure sh_word_split is on
       [[ -o shwordsplit ]] && SHWORDSPLIT_ON=true
       setopt shwordsplit
@@ -227,7 +227,7 @@ EOF
     done
 
     # Turn off shwordsplit unless it was on previously
-    if [[ $shell == "zsh" && -z $SHWORDSPLIT_ON ]]; then unsetopt shwordsplit; fi
+    if breeze_shell_is "zsh" && [[ -z $SHWORDSPLIT_ON ]]; then unsetopt shwordsplit; fi
   }
 
   # Setup aliases
diff --git a/lib/git/status_shortcuts.sh b/lib/git/status_shortcuts.sh
index a8616ce6..9f40e53a 100644
--- a/lib/git/status_shortcuts.sh
+++ b/lib/git/status_shortcuts.sh
@@ -8,7 +8,6 @@
 # Numbered file shortcuts for git commands
 # ------------------------------------------------------------------------------
 
-
 # Processes 'git status --porcelain', and exports numbered
 # env variables that contain the path of each affected file.
 # Output is also more concise than standard 'git status'.
@@ -17,6 +16,11 @@
 # 1 || staged,  2 || unmerged,  3 || unstaged,  4 || untracked
 # --------------------------------------------------------------------
 git_status_shortcuts() {
+  if [ "${scmbDebug:-}" = "true" ]; then
+    set -x
+    trap "set +x;" RETURN
+  fi
+
   fail_if_not_git_repo || return 1
   zsh_compat # Ensure shwordsplit is on for zsh
   git_clear_vars
@@ -50,8 +54,6 @@ git_status_shortcuts() {
   zsh_reset # Reset zsh environment to default
 }
 
-
-
 # 'git add' & 'git rm' wrapper
 # This shortcut means 'stage the change to the file'
 # i.e. It will add new and changed files, and remove deleted files.
@@ -155,8 +157,8 @@ scmb_expand_args() {
 _print_path() {
   local pathname
   pathname=$(eval printf '%s' "\"\${$2}\"")
-  if [ "$1" = 1 ]; then  # print relative
-    pathname=${pathname#$PWD/}  # Remove $PWD from beginning of the path
+  if [ "$1" = 1 ]; then        # print relative
+    pathname=${pathname#$PWD/} # Remove $PWD from beginning of the path
   fi
   printf '%s' "$pathname"
 }
@@ -183,7 +185,6 @@ git_clear_vars() {
   done
 }
 
-
 # Shortcuts for resolving merge conflicts.
 _git_resolve_merge_conflict() {
   if [ -n "$2" ]; then
@@ -216,7 +217,7 @@ git_commit_prompt() (
     saved_commit_msg="$(cat /tmp/.git_commit_message~)"
     echo -e "\033[0;36mLeave blank to use saved commit message: \033[0m$saved_commit_msg"
   fi
-  if [[ $shell == "zsh" ]]; then
+  if breeze_shell_is "zsh"; then
     vared -h -p "Commit Message: " commit_msg
   else
     read -r -e -p "Commit Message: " commit_msg
@@ -242,7 +243,7 @@ git_commit_prompt() (
   escaped_msg=$(echo "$commit_msg" | sed -e 's/"/\\"/g' -e "s/!/\"'!'\"/g")
   # Add command to bash history, so that if a git pre-commit hook fails,
   # you can just press "up" and "return" to retry the commit.
-  if [[ $shell == "zsh" ]]; then
+  if breeze_shell_is "zsh"; then
     # zsh's print needs double escaping
     print -s "git commit -m \"${escaped_msg//\\/\\\\}\""
   else
@@ -252,14 +253,14 @@ git_commit_prompt() (
   fi
 
   # Also save the commit message to a temp file in case git commit fails
-  echo "$commit_msg" > "/tmp/.git_commit_message~"
+  echo "$commit_msg" >"/tmp/.git_commit_message~"
   eval $@ # run any prequisite commands
 
   echo "$commit_msg" | git commit -F - | tail -n +2
 
   # Fetch the pipe status (for both bash and zsh):
   GIT_PIPE_STATUS=("${PIPESTATUS[@]}${pipestatus[@]}")
-  if [[ $shell == "zsh" ]]; then
+  if breeze_shell_is "zsh"; then
     git_exit_status="${GIT_PIPE_STATUS[2]}" # zsh array indexes start at 1
   else
     git_exit_status="${GIT_PIPE_STATUS[1]}"
diff --git a/lib/git/tools.sh b/lib/git/tools.sh
index c158a772..313c6276 100644
--- a/lib/git/tools.sh
+++ b/lib/git/tools.sh
@@ -10,7 +10,6 @@
 #   at https://github.com/ndbroadbent/scm_breeze
 # -----------------------------------------------------------------
 
-
 # Remove files/folders from git history
 # -------------------------------------------------------------------
 # To use it, cd to your repository's root and then run the function
@@ -30,7 +29,6 @@ git_remove_history() {
   rm -rf .git/refs/original/ && $_git_cmd reflog expire --all &&  $_git_cmd gc --aggressive --prune
 }
 
-
 # Set default remote and merge for a git branch (pull and push)
 # Usage: git_set_default_remote(branch = master, remote = origin)
 git_set_default_remote() {
@@ -68,8 +66,6 @@ git_exclude_basename() {
   exec_scmb_expand_args __git_exclude_basename "$@"
 }
 
-
-
 # Use git bisect to find where text was removed from a file.
 #
 # Example:
@@ -91,7 +87,6 @@ git_bisect_grep() {
   $_git_cmd bisect run grep -qRE "$2" $search_path
 }
 
-
 # Removes a git submodule
 # (from http://stackoverflow.com/a/7646931/304706)
 # Deletes the sections from .gitmodules, .git/config,
@@ -108,7 +103,6 @@ git_submodule_rm() {
   $_git_cmd rm --cached "$1"
 }
 
-
 # Swaps git remotes
 # i.e. swap origin <-> username
 git_swap_remotes() {
@@ -122,11 +116,10 @@ git_swap_remotes() {
   echo "Swapped $1 <-> $2"
 }
 # (use git fetch tab completion)
-if [ "$shell" = "bash" ]; then
+if breeze_shell_is "bash"; then
   complete -o default -o nospace -F _git_fetch git_swap_remotes
 fi
 
-
 # Delete a git branch from local, cached remote and remote server
 git_branch_delete_all() {
   if [ -z "$1" ]; then
diff --git a/lib/scm_breeze.sh b/lib/scm_breeze.sh
index 2744b007..f5a06ed0 100644
--- a/lib/scm_breeze.sh
+++ b/lib/scm_breeze.sh
@@ -1,13 +1,48 @@
 # Detect shell
-if [ -n "${ZSH_VERSION:-}" ]; then shell="zsh"; else shell="bash"; fi
+breeze_detect_shell() {
+  if [ -n "${ZSH_VERSION:-}" ]; then
+    echo "zsh"
+  else
+    echo "bash"
+  fi
+}
+
+breeze_shell_is() {
+  [ "$(breeze_detect_shell)" = "$1" ] && return 0
+  return 1
+}
 # Detect whether zsh 'shwordsplit' option is on by default.
-if [ $shell = "zsh" ]; then zsh_shwordsplit=$( (setopt | grep -q shwordsplit) && echo "true" ); fi
+if breeze_shell_is "zsh"; then
+  zsh_shwordsplit=$( (setopt | grep -q shwordsplit) && echo "true")
+fi
+
 # Switch on/off shwordsplit for functions that require it.
-zsh_compat(){ if [ $shell = "zsh" ] && [ -z $zsh_shwordsplit ]; then setopt shwordsplit; fi; }
-zsh_reset(){  if [ $shell = "zsh" ] && [ -z $zsh_shwordsplit ]; then unsetopt shwordsplit; fi; }
+zsh_compat() {
+  if breeze_shell_is "zsh" && [ -z $zsh_shwordsplit ]; then
+    setopt shwordsplit
+  fi
+}
+zsh_reset() {
+  if breeze_shell_is "zsh" && [ -z $zsh_shwordsplit ]; then
+    unsetopt shwordsplit
+  fi
+}
+
 # Enable/disable nullglob for zsh or bash
-enable_nullglob()  { if [ $shell = "zsh" ]; then setopt NULL_GLOB;   else shopt -s nullglob; fi; }
-disable_nullglob() { if [ $shell = "zsh" ]; then unsetopt NULL_GLOB; else shopt -u nullglob; fi; }
+enable_nullglob() {
+  if breeze_shell_is "zsh"; then
+    setopt NULL_GLOB
+  else
+    shopt -s nullglob
+  fi
+}
+disable_nullglob() {
+  if breeze_shell_is "zsh"; then
+    unsetopt NULL_GLOB
+  else
+    shopt -u nullglob
+  fi
+}
 
 # Alias wrapper that ignores errors if alias is not defined.
 _safe_alias(){ alias "$@" 2> /dev/null; }
@@ -31,7 +66,7 @@ function token_quote {
   # Keep this code for use when minimum versions of {ba,z}sh can be increased.
   # See https://github.com/scmbreeze/scm_breeze/issues/260
   #
-  # if [[ $shell = bash ]]; then
+  # if breeze_detect_shell "bash"; then
   #   # ${parameter@operator} where parameter is ${@} and operator is 'Q'
   #   # https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html
   #   eval "${@@Q}"
@@ -50,7 +85,7 @@ function _safe_eval() {
   # Keep this code for use when minimum versions of {ba,z}sh can be increased.
   # See https://github.com/scmbreeze/scm_breeze/issues/260
   #
-  # if [[ $shell = bash ]]; then
+  # if breeze_detect_shell "bash"; then
   #   # ${parameter@operator} where parameter is ${@} and operator is 'Q'
   #   # https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html
   #   eval "${@@Q}"
@@ -60,8 +95,8 @@ function _safe_eval() {
   # fi
 }
 
-find_binary(){
-  if [ $shell = "zsh" ]; then
+find_binary() {
+  if breeze_shell_is "bash"; then
     builtin type -p "$1" | sed "s/$1 is //" | head -1
   else
     builtin type -P "$1"
diff --git a/test/lib/git/status_shortcuts_test.sh b/test/lib/git/status_shortcuts_test.sh
index d24ed231..5ba6a7b5 100755
--- a/test/lib/git/status_shortcuts_test.sh
+++ b/test/lib/git/status_shortcuts_test.sh
@@ -335,7 +335,7 @@ test_git_commit_prompt() {
   assertIncludes "$git_show_output" "$commit_msg"
 
   # Test that history was appended correctly.
-  if [[ $shell == "zsh" ]]; then
+  if breeze_shell_is "zsh"; then
     test_history="$(history)"
     # TODO(ghthor): zsh isn't working here
     # assertIncludes "$test_history" "git commit -m \"$dbl_escaped_msg\""
@@ -371,7 +371,7 @@ test_git_commit_prompt_with_append() {
   assertIncludes "$git_show_output" "$commit_msg \[ci skip\]"
 
   # Test that history was appended correctly.
-  if [[ $shell == "zsh" ]]; then
+  if breeze_shell_is "zsh"; then
     test_history="$(history)"
     # TODO(ghthor): zsh isn't working here
     # assertIncludes "$test_history" "$commit_msg \[ci skip\]"